The new ionically-conductive cathode enabled the ORNL battery to maintain a capacity of 1200 milliamp-hours (mAh) per gram after 300 charge-discharge cycles at 60 degrees Celsius. For comparison, a traditional lithium-ion battery cathode has an average capacity between 140-170 mAh/g. Because lithium-sulfur batteries deliver about half the voltage of lithium-ion versions, this eight-fold increase in capacity demonstrated in the ORNL battery cathode translates into four times the gravimetric energy density of lithium-ion technologies, explained Liang.

... The new ionically-conductive cathode enabled the ORNL battery to maintain a capacity of 1200 milliamp-hours (mAh) per gram after 300 charge-discharge cycles at 60 degrees Celsius. ...

Well, in bold print and underlined you see the catch of this solid electrolyte. Even LiFePO4 likes it warm and cozy: at +40°C their power capabilites are phenomenal compared to at +10°C. But they will work at even lower cell temperatures. 60°C is pretty warm already, requiring battery pre-heating, excellent thermal insulation as well as some kind of thermal management for the battery.
That was and is, on an even higher level (over 300°C!), the problem of the South-African "Zebra" battery, which uses molten sodium aluminumchloride as electrolyte...

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My rides:
QvR vR one: a Swiss package of pure understatement - innocent and to some eyes (from some angles) exceedingly ugly looks, but with raw and hardly containable electron power up to real 95 to 100km/h! And a literally rock-hard suspension due to a carrying capacity of twice it's unladen weight... Now converted to more controllable and efficient brushless motor and vector-contoller.

E-Sprit Fury (basis is the Erider Thunder 5000) since May 03, 2011. Highly moded - but now in active retirement

The paper does mention a relatively low energy efficiency : 83% at 60°C and only 60% at room temperature (25°C). It does sound like it would need insulation/heat to stay warm but still functions at lower temps. If you still just had 60% of the capacity, it is still more per weight than the alternatives.

Looks encouraging, but still only viable at the lab scale and at least another 3 years away from commercial realisation. Questions which I can think of as an engineer, which still need to be answered:

- Volumetric energy density: Sure, specific of energy (energy / kg) numbers look great, but if a 5lb battery's the size of a shipping container, it isn't going to work.
- Safety: Being 'safer' than commercial Lithium chemistries was mentioned a couple of times, but no indication or suggestion of HOW this chemistry might be safer. Sulphur is after all, toxic (as is pretty much every metal used in modern batteries).
- Cost: Yes, sulphur is practically free, but I the same is true of Nitrogen and Oxygen (air), yet pure, compressed Nitrogen or Oxygen (typically required by industries), isn't.
- Mechanical durability: Kick it, and see if anything happens to it.
- Power output: Effectively, what is the internal resistance of a Sulphur-based battery?

And most importantly:

- Scalability of manufacturing: Yes, you can make the stuff in the lab, but how easy is it to produce in the tonnes per month scale (which will be necessary to keep costs low; presumably this stuff will be revolutionary, so everyone will want to get their hands on it, so you are going to need to be able to make this in very large volumes or the laws of supply and demand are going to drive prices up).

There are plenty of competing technologies with great headlines for either volumetric or specific energy density. Not all of them will make it to go commercial, but it's encouraging to know that we're going to see the possibility of several fundamentally game changing battery chemistries showing up in the next 3-5 years.